1. Field of the Invention
The present invention relates to a method of driving a plasma display panel (hereinafter also referred to as xe2x80x9cPDPxe2x80x9d) and a plasma display device, and more particularly, it relates to a technique of reducing the scale of a common driver, reducing the cost and saving power.
2. Description of the Background Art
FIG. 22 is a block diagram typically showing the overall structure of a conventional plasma display device as first prior art. This structure is disclosed in Japanese Patent Laying-Open Gazette No. 7-160218 (1995) (Japanese Patent No. 2772753), for example. As shown in FIG. 22, a control circuit 106 generates prescribed control signals on the basis of an input clock signal CLK, image data DATA, a vertical synchronizing signal VSYNC and a horizontal synchronizing signal HSYNC and outputs the control signals to an address driver 105, a Y common driver 102, a scan driver 103 and an X common driver 104. The circuits 102, 103, 104, 105 and 106 are supplied with prescribed voltages generated in a power supply circuit 107.
The X common driver 104 and the address driver 105 generate prescribed voltages on the basis of the control signals from the control circuit 106 respectively, and output the voltages to sustain electrodes X1 to XN and address electrodes A1 to AM of three electrode plane discharge alternating plasma display panel (AC-PDP) 101 connected to output terminals of the respective drivers. The N sustain electrodes X1 to XN are connected in common (therefore, these electrodes are also generically referred to as xe2x80x9csustain electrodes Xxe2x80x9d) and subjected to application of the same voltage. The Y common driver 102 generates a prescribed voltage on the basis of the control signal from the control circuit 106 and supplies the voltage to scan electrodes Y1 to YN through the scan driver 103 for the PDP 101.
FIG. 23 is a longitudinal sectional view of the PDP 101 disclosed in the aforementioned gazette. This figure illustrates the structure of a discharge cell C formed on the (three-dimensional) intersection between each pair of electrodes formed by each sustain electrode and each scan electrode and each address electrode shown in FIG. 22.
As shown in FIG. 23, the PDP 101 has a front substrate 151 and a back substrate (or rear substrate) 161 arranged in parallel with each other through a discharge space 160. A strip-shaped sustain electrode Xi (i: 1 to N) and a strip-shaped scan electrode Yi arranged in parallel with each other to define an electrode pair are formed on the surface of the front substrate 151 closer to the discharge space 160 along the direction perpendicular to the plane of FIG. 23. A dielectric or insulating layer 152 is formed to cover the aforementioned electrodes Xi and Yi and the aforementioned surface of the front substrate 151. A protective film 155 consisting of a high secondary electron emission material such as magnesium oxide (MgO) is formed on the surface of the dielectric layer 152 closer to the discharge space 160.
On the other hand, each strip-shaped address electrode Ak (k: 1 to M) is formed on the surface of the back substrate 161 closer to the discharge space 160 along the direction parallel to the plane of FIG. 23 (see FIGS. 22 and 23). A plurality of strip-shaped barrier ribs 163 are formed perpendicularly across the address electrode Ak, i.e., along the direction perpendicular to the plane of FIG. 23 (the barrier ribs 163 may alternatively be formed in parallel with the address electrode Ak along cell boundaries).
A fluorescent substance layer 164 is formed on a region of the aforementioned surface of the back substrate 161 (and on the address electrode Ak) having no barrier ribs 163 (the fluorescent substance layer 164 may also be formed on side wall surfaces of the barrier ribs 163). A dielectric or insulating layer may be formed on the surface of the fluorescent substance layer 164 closer to the back substrate 163 to cover the aforementioned surface of the back substrate 161 and the address electrode Ak.
A method of driving the AC-PDP disclosed in the aforementioned gazette is now described. FIG. 24 is a timing chart showing the waveforms of the voltages applied to the respective electrodes in this driving method in a period of one subfield in a subfield gradation method.
As shown in FIG. 24, one subfield is divided into (a) a reset period for erasing wall charges remaining as the display history in a preceding subfield, (b) an address period for applying wall charges based on image data to discharge cells for generating display emission forming image display in a sustain period described later, and (c) a sustain discharge period or the sustain period for generating sustain discharge in the discharge cells storing the wall charges in the address period and performing display emission.
In the reset period, a full write pulse 24 is applied to the sustain electrode Xi at a time ta for generating discharge in all discharge cells. The full write pulse 24 is also referred to as a priming pulse. At a time tb when the full write pulse 24 falls, self-erase discharge is generated to erase wall charges of all discharge cells. In the subsequent address period, a scan pulse 21 is sequentially applied to the scan electrodes Y1 to YN (at a time tc, for example) while an address pulse 22 based on the input image data DATA (see FIG. 22) is applied to the address electrodes A1 to AM. Thus, address discharge is generated in discharge cells to be turned on for display in the sustain period for storing wall charges in the discharge cells. In the subsequent sustain period, a sustain pulse 23 is alternately applied to the scan electrode Yi and the sustain electrode Xi (see times td and te). At this time, only the discharge cells storing wall charges due to the aforementioned address discharge cause sustain discharge performing image display immediately after the rise of the sustain pulse 23.
In the conventional driving method, the priming pulse 24 and the sustain pulse 23 are generated in the X common driver 104 and the Y common driver 102 and simultaneously applied to the full screen of the PDP. At this time, discharge simultaneously starts on the full screen or in all discharge cells, and hence the X common driver 104 and the Y common driver 102 supply an extremely large peak current to the PDP. The value of this peak current may reach 200 A in a PDP of 100 cm diagonal (type 40), for example. Therefore, circuits forming the common drivers 104 and 102 disadvantageously have remarkable power loss. Further, the X common driver 104 and the Y common driver 102 are required to have ability of supplying the current having the aforementioned large peak. Therefore, the X common driver 104 and the Y common driver 102 must be increased in circuit scale, to disadvantageously result in increase of the cost or the price of the common drivers 104 and 102 and the plasma display device.
Japanese Patent Laying-Open Gazette No. 7-64508 (1995) proposes an exemplary method capable of solving such problems. FIG. 25 is a model diagram showing the structure of a plasma display device proposed in this gazette as second prior art. As shown in FIG. 25, the plasma display device according to the second prior art divides sustain electrodes X1 to X2n and scan electrodes Y1 to Y2n into two blocks, i.e., a block 201a including the sustain electrodes X1 to Xn and the scan electrodes Y1 to Yn and a block 201b including the sustain electrodes Xn+1 to X2n and the scan electrodes Yn+1 to Y2n, and is provided with dedicated sustain drivers (corresponding to the common drivers in the aforementioned conventional plasma display device) 202a, 202b, 204A and 204B for the respective blocks 201a and 201b. Referring to FIG. 25, a PDP 201, an address driver 205 and scan drivers 203a and 203b correspond to the PDP 101, the address driver 105 and the scan driver 103 shown in FIG. 22 respectively. The aforementioned gazette according to the second prior art states that the aforementioned peak current can be reduced to half that in the aforementioned conventional plasma display device by staggering the timing for each discharge in the aforementioned two blocks 201a and 201b. According to the structure shown in FIG. 25 and the aforementioned driving method, it is possible to reduce the scale of a power supply device in the plasma display device since the peak value of the power supply current, i.e., the current flowing in the sustain drivers 202a, 202b, 204A and 204B can be reduced to half that in the common drivers 102 and 104 (see FIG. 22) of the conventional plasma display device. However, the peak current half that in the conventional plasma display device flows to each of the divided sustain drivers 202a and 202b or 204A and 204B, and hence the scale of the sustain drivers required for the overall plasma display device is (sustain driver of xc2xd in scale)xc3x97(two blocks). In other words, it can be said that the circuit scale of the overall sustain drivers in the plasma display device according to the second prior art is substantially identical to that of the conventional plasma display device.
FIG. 26 is a timing chart related to a method of driving a plasma display device disclosed in Japanese Patent Laying-Open Gazette No. 7-319424 (1995) as third prior art. In this driving method, scan electrodes Y1 to YN are divided into n blocks while pulse voltages out of phase with each other are applied to the respective blocks (see times tp2 to tp11), as shown in FIG. 26. The aforementioned gazette according to the third prior art states that the peak value of the discharge current can be reduced to 1/n. It is indeed conceivable that the scale of common drivers not divided into blocks can be reduced to 1/n. However, the scale of common drivers divided into blocks is substantially identical to that of the conventional plasma display device for a reason similar to that in the case of the second prior art.
In a plasma display device disclosed in Japanese Patent Laying-Open Gazette No. 6-43829 (1994) as fourth prior art, one frame period is divided into an odd field and an even field for performing driving every other row, as shown in FIG. 27. According to this field structure, it is conceivable that peak current suppliability of sustain drivers may be half that in the conventional plasma display device since the peak current in discharge can be reduced to half that in the conventional plasma display device and the sustain drivers are not divided. However, display emission or display lighting is performed every other row and hence the number of sustain pulses per unit time, i.e., a sustain frequency must be twice that in the conventional plasma display device in order to attain the same brightness as the conventional plasma display device. When the sustain frequency is doubled, however, reactive power generated when charging/discharging capacitance components between electrodes of the PDP is disadvantageously doubled as compared with the conventional plasma display device.
As hereinabove described, it is difficult to reduce the circuit scale of common drivers or sustain drivers in the plasma display device according to the second, third, or fourth prior art as compared with that in the conventional plasma display device. Although the circuit scale of the common drivers can be reduced in the plasma display device according to the fourth prior art, another problem arises such that reactive power increases.
A driving method according to a first aspect of the present invention is a method of driving a plasma display panel comprising a plurality of first electrodes arranged in parallel with each other and a plurality of second electrodes each pairing with each first electrode for forming prescribed discharge in a discharge space between each pair of electrodes formed by the first electrode and the second electrode while the plurality of pairs of electrodes are divided into (sxc3x97t (s and t: integer of at least 2)) electrode pair groups with combination of the plurality of first electrodes divided into s first electrode groups and the plurality of second electrodes divided into t second electrode groups, and the prescribed discharge in the (sxc3x97t) electrode pair groups is generated in units of the electrode pair groups at staggered timing.
(1) According to the first aspect, the prescribed discharge is generated in the (sxc3x97t) electrode pair groups at staggered timing, whereby a peak current in the discharge can be reduced to 1/(sxc3x97t) as compared with the peak current in the conventional driving method simultaneously generating discharge in the overall pairs of electrodes or on the full screen of the plasma display panel. Therefore, the aforementioned peak current for all first electrodes can be reduced to 1/t that in the conventional driving method, and the aforementioned peak current for all second electrodes can be reduced to 1/s. Consequently, it is possible to reduce a substantial peak current flowing in each driver circuit connected to each of the first and second electrodes for supplying a prescribed driving voltage or voltage pulse to the electrodes, i.e., current suppliability of each driver circuit to 1/t or to 1/s as compared with the conventional driver circuit. Therefore, it is possible to provide a method of driving a plasma display panel capable of implementing miniaturization of each driver circuit, cost reduction and reduction of power consumption.
In a driving method according to a second aspect of the present invention which is the method of driving a plasma display panel according to the first aspect, the prescribed discharge in the (sxc3x97t) electrode pair groups is generated without simultaneously generating discharge in a plurality of first electrode groups among the s first electrode groups and without simultaneously generating discharge in a plurality of second electrode groups among the t second electrode groups.
(2) According to the second aspect, discharge of the plasma display panel is executed (i) so that no discharge is simultaneously generated in a plurality of first electrode groups among the s first electrode groups, (ii) without simultaneously generating discharge in a plurality of second electrode groups among the t second electrode groups. When simultaneously generating discharge in a plurality of electrode pair groups among the (sxc3x97t) electrode pair groups while satisfying the aforementioned conditions (i) and (ii), therefore, the time required for discharge executed on the overall surface of the plasma display panel, such as a time required for sustain discharge in a subfield gradation method (i.e., a sustain period), for example, can be reduced as compared with the driving method according to the first aspect, in addition to the aforementioned effect (1).
According to the second aspect, further, the number of voltage pulses applied to the first and second electrodes respectively for the discharge executed on the overall surface of the plasma display panel such as the aforementioned sustain discharge, for example, can be reduced as compared with that in the driving method according to the first aspect. Thus, reactive power can be further reduced when driving the plasma display panel. According to the second aspect of the present invention, therefore, it is possible to provide a plasma display device with smaller power consumption as compared with a plasma display device comprising the plasma display panel driven by the driving method according to the first aspect.
A driving method according to a third aspect of the present invention is the method of driving a plasma display panel according to the first or second aspect, and the plurality of first electrodes are divided into two first electrode groups and the plurality of second electrodes are divided into two second electrode groups, the plurality of electrode pair groups are divided into a first electrode pair group formed by one of the first electrode groups and one of the second electrode groups, a second electrode pair group formed by the one of the first electrode groups and the other of the second electrode groups, a third electrode pair group formed by the other of the first electrode groups and the one of the second electrode groups, and a fourth electrode pair group formed by the other of the first electrode groups and the other of the second electrode groups, while the method comprises steps of simultaneously generating the prescribed discharge in the first electrode pair group and the fourth electrode pair group, and simultaneously generating the prescribed discharge in the second electrode pair group and the third electrode pair group.
(3) According to the third aspect, an effect similar to the aforementioned effect (1) or (2) can be attained. When the first and second electrodes are arranged in parallel with each other to form display lines or scan lines of the plasma display panel and the first and fourth electrode pair groups are made to correspond to odd rows (or even rows) of the display lines in the plasma display panel while the second and third electrode pair groups are made to correspond to the even rows (or the odd rows) of the display lines, the prescribed discharge can be alternately generated in the odd-row and even-row display lines. Therefore, it is possible to provide a driving method optimum for an interlace signal for a TV image or the like.
A driving method according to a fourth aspect of the present invention is the method of driving a plasma display panel according to the third aspect, and the first electrodes and the second electrodes are arranged in parallel with each other, while either the one of the first electrode groups or the one of the second electrode groups forms one of electrodes in any odd or even pairs of electrodes among the plurality of pairs of electrodes arranged in parallel with each other.
(4) According to the fourth aspect, it is possible to implement image display optimum for an interlace signal for a TV image or the like while attaining an effect similar to the aforementioned effect (3), i.e., similar to the aforementioned effect (1) or (2) when the first and second electrodes are arranged in parallel with each other to form display lines or scan lines of the plasma display panel.
A driving method according to a fifth aspect of the present invention is the method of driving a plasma display panel according to the fourth aspect, and one frame period for image display is divided into a period generating discharge in the odd pairs of electrodes and a period generating discharge in the even pairs of electrodes.
(5) According to the fifth aspect, the duty ratio of a driving pulse supplied to each electrode can be arbitrarily set, whereby it is possible to improve the degree of freedom in the driving method for the prescribed discharge such as the aforementioned sustain discharge, for example, or the driving method in a sustain period.
A driving method according to a sixth aspect of the present invention is a method of driving a plasma display panel comprising a plurality of first electrodes arranged in parallel with each other and a plurality of second electrodes arranged in a direction three-dimensionally intersecting with the plurality of first electrodes through a discharge space for forming prescribed discharge in each discharge cell formed on each of the three-dimensional intersections, and the plurality of first electrodes are divided into two first electrode groups and the plurality of second electrodes are divided into two second electrode groups while a plurality of discharge cells are divided into a first discharge cell group formed on the three-dimensional intersection between one of the first electrode groups and one of the second electrode groups, a second discharge cell group formed on the three-dimensional intersection between the one of the first electrode groups and the other of the second electrode groups, a third discharge cell group formed on the three-dimensional intersection between the other of the first electrode groups and the one of the second electrode groups, and a fourth discharge cell group formed on the three-dimensional intersection between the other of the first electrode groups and the other of the second electrode groups, and the method comprises steps of simultaneously generating the prescribed discharge in the first discharge cell group and the fourth discharge cell group, and simultaneously generating the prescribed discharge in the second discharge cell group and the third discharge cell group.
(6) According to the sixth aspect, an effect similar to the aforementioned effect (1) or (2) can be attained also in a plasma display panel having first and second electrodes arranged in three-dimensionally intersecting directions through a discharge space with discharge cells formed on the three-dimensional intersections respectively, i.e., the so-called opposite two-electrode plasma display panel.
In a driving method according to a seventh aspect of the present invention, which is the method of driving a plasma display panel according to any of the first to fifth aspects, an image display time for one screen is divided into a plurality of subfields and then priming discharge, erase discharge, write discharge based on input image data and sustain discharge are generated in the discharge space in each of the plurality of subfields, and the prescribed discharge is at least one of the priming discharge, the erase discharge and the sustain discharge.
(7) According to the seventh aspect, prescribed discharge is discharge simultaneously generated for the overall surface of the plasma display panel in the conventional driving method in the so-called subfield gradation method. At least one of priming discharge, erase discharge and sustain discharge corresponds. Therefore, any of the aforementioned effects (1) to (6) can be attained.
In a driving method according to an eighth aspect of the present invention, which is the method of driving a plasma display panel according to the sixth aspect, an image display time for one screen is divided into a plurality of subfields and then priming discharge, erase discharge, write discharge based on input image data and sustain discharge are generated in the discharge space in each of the plurality of subfields, and the prescribed discharge is at least one of the priming discharge, the erase discharge and the sustain discharge.
(8) According to the eighth aspect, an effect similar to the aforementioned effect (7) can be attained.
The present invention is also directed to a plasma display device. A plasma display device according to a ninth aspect of the present invention comprises a plasma display panel including a plurality of first electrodes arranged in parallel with each other and a plurality of second electrodes each pairing with each first electrode for forming prescribed discharge in a discharge space between each pair of electrodes formed by the first electrode and the second electrode, and a driving device connected to the plurality of first electrodes and the plurality of second electrodes for supplying a driving voltage to each first electrode and each second electrode, while the plurality of pairs of electrodes are divided into (sxc3x97t (s and t: integer of at least 2)) electrode pair groups with combination of the plurality of first electrodes divided into s first electrode groups and the plurality of second electrodes divided into t second electrode groups, and the driving device generates and outputs the driving voltage generating each prescribed discharge in each of the (sxc3x97t) electrode pair groups in units of the electrode pair groups at staggered timing.
(9) According to the ninth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (1).
A plasma display device according to a tenth aspect of the present invention is the plasma display device according to the ninth aspect, and the driving unit generates and outputs the driving voltage generating the prescribed discharge in each of the (sxc3x97t) electrode pair groups without simultaneously generating discharge in a plurality of first electrode groups among the s first electrode groups and without simultaneously generating discharge in a plurality of second electrode groups among the t second electrode groups.
(10) According to the tenth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (2).
A plasma display device according to an eleventh aspect of the present invention is the plasma display device according to the ninth or tenth aspect, and the plurality of first electrodes are divided into two first electrode groups and the plurality of second electrodes are divided into two second electrode groups, while the plurality of electrode pair groups are divided into a first electrode pair group formed by one of the first electrode groups and one of the second electrode groups, a second electrode pair group formed by the one of the first electrode groups and the other of the second electrode groups, a third electrode pair group formed by the other of the first electrode groups and the one of the second electrode groups, and a fourth electrode pair group formed by the other of the first electrode groups and the other of the second electrode groups, and the driving device generates and outputs the driving voltage simultaneously generating the prescribed discharge in the first electrode pair group and the fourth electrode pair group, and generates and outputs the driving voltage simultaneously generating the prescribed discharge in the second electrode pair group and the third electrode pair group.
(11) According to the eleventh aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (3).
A plasma display device according to a twelfth aspect of the present invention is the plasma display device according to the eleventh aspect, and the first electrodes and the second electrodes are arranged in parallel with each other, while either the one of the first electrode groups or the one of the second electrode groups forms one of electrodes in any odd or even pairs of electrodes among the plurality of pairs of electrodes arranged in parallel with each other.
(12) According to the twelfth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (4).
A plasma display device according to a thirteenth aspect of the present invention is the plasma display device according to the twelfth aspect, and the driving device divides one frame period for image display into a period generating discharge in the odd pairs of electrodes and a period generating discharge in the even pairs of electrodes and then generates and outputs the driving voltage.
(13) According to the thirteenth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (5).
A plasma display device according to a fourteenth aspect of the present invention comprises a plasma display panel including a plurality of first electrodes arranged in parallel with each other and a plurality of second electrodes arranged in a direction three-dimensionally intersecting with the plurality of first electrodes through a discharge space for forming prescribed discharge in each discharge cell formed on each of the three-dimensional intersections, and a driving device connected to the plurality of first electrodes and the plurality of second electrodes for supplying a driving voltage to each first electrode and each second electrode, while the plurality of first electrodes are divided into two first electrode groups and the plurality of second electrodes are divided into two second electrode groups, a plurality of discharge cells are divided into a first discharge cell group formed on the three-dimensional intersection between one of the first electrode groups and one of the second electrode groups, a second discharge cell group formed on the three-dimensional intersection between the one of the first electrode groups and the other of the second electrode groups, a third discharge cell group formed on the three-dimensional intersection between the other of the first electrode groups and the one of the second electrode groups, and a fourth discharge cell group formed on the three-dimensional intersection between the other of the first electrode groups and the other of the second electrode groups, and the driving device generates and outputs the driving voltage simultaneously generating the prescribed discharge in the first discharge cell group and the fourth discharge cell group, and generates and outputs the driving voltage simultaneously generating the prescribed discharge in the second discharge cell group and the third discharge cell group.
(14) According to the fourteenth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (6).
A plasma display device according to a fifteenth aspect of the present invention is the plasma display device according to any of the ninth to thirteenth aspects, and when the driving device divides an image display time for one screen into a plurality of subfields and then generates and outputs the driving voltage for generating priming discharge, erase discharge, write discharge based on input image data and sustain discharge in the discharge space in each of the plurality of subfields, the prescribed discharge is at least one of the priming discharge, the erase discharge and the sustain discharge.
(15) According to the fifteenth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (7).
A plasma display device according to a sixteenth aspect of the present invention is the plasma display device according to the fourteenth aspect, and when the driving device divides an image display time for one screen into a plurality of subfields and then generates and outputs the driving voltage for generating priming discharge, erase discharge, write discharge based on input image data and sustain discharge in the discharge space in each of the plurality of subfields, the prescribed discharge is at least one of the priming discharge, the erase discharge and the sustain discharge.
(16) According to the sixteenth aspect, it is possible to provide a plasma display device attaining an effect similar to the aforementioned effect (8).
A first object of the present invention is to provide a method of driving a plasma display panel capable of reducing a peak current in discharge as compared with the conventional plasma display device.
A second object of the present invention is to provide a method of driving a plasma display panel capable of implementing miniaturization of a driver circuit supplying a voltage to each electrode, cost reduction and reduction of power consumption while attaining the aforementioned first object.
A third object of the present invention is to provide a method of driving a plasma display panel optimum for an interlace signal while attaining the aforementioned first and second objects.
A fourth object of the present invention is to provide a plasma display device facilitated in miniaturization, cost reduction and reduction of power consumption as compared with the conventional plasma display device by comprising a plasma display panel driven by a driving method capable of attaining the aforementioned first to third objects.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.